A Novel Self-Assembled Graphene-Based Flame Retardant: Synthesis and Flame Retardant Performance in PLA

In this study, a novel flame retardant (PMrG) was developed by self-assembling melamine and phytic acid (PA) onto rGO, and then applying it to the improvement of the flame resistance of PLA. PMrG simultaneously decreases the peak heat release rate (pHRR) and the total heat release (THR) of the composite during combustion, and enhances the LOI value and the time to ignition (TTI), thus significantly improving the flame retardancy of the composite. The flame retardant mechanism of the PMrG is also investigated. On one hand, the dehydration of PA and the decomposition of melamine in PMrG generate non-flammable volatiles, such as H2O and NH3, which dilute the oxygen concentration around the combustion front of the composite. On the other hand, the rGO, melamine, and PA components in PMrG create a synergistic effect in promoting the formation of a compact char layer during the combustion, which plays a barrier role and effectively suppresses the release of heat and smoke. In addition, the PMrGs in PLA exert a positive effect on the crystallization of the PLA matrix, thus playing the role of nucleation agent.

Numerical simulation of thermal diamond filter for working station 1-5 of synchrotron “SKIF“

Numerical 3D-simulations of thermal loads of thermal diamond filter for the working station 1-5 of synchrotron “SKIF” has been performed. An efficient version of a water-cooling system of a CVD diamond by means of mini-channels in copper flanges with a total heat release power of 1290 W is presented. The influence of various configurations of the cooling system, different boundary conditions (thermal insulation, radiation heat exchange), water supply pressure on the maximum temperature in diamond wafer has been investigated. The influence of the temperature dependence of the properties of diamond glass has been studied. The maximum temperature on the diamond wafer is found to be 317.6 °C absorbing 1290 W of power correspond to the safe mode for some specific cooling system configuration. The corresponding flow rate of 7 °C cooling water was 13.1 l/min.

Cone calorimetric fire properties and thermal analysis of polyester-banana peduncle fibre composite fused with bio-fire retardant additive

Background Lately, thermoplastic and thermoset polymers are integrated with natural fillers to harvest composites. Due to an excellent property profile, these composites find wide applications in engineering fields. This research work aimed to investigate the parameters that influence the thermal degradation of Polyester-Banana peduncle fibre-reinforced composite incorporated with cow horn ash particle (CHAp) as a fire retardant additive and optimize the total heat produced for the smaller the better. The major instruments used in this study were cone calorimeter and the thermogravimetric analyser. Result The parameters considered were time, reinforcement type, and weight per cent of reinforcement material. The composites were made by varying the ratios of CHAp and BPF in the polyester matrix from 0:0, 2.5:2.5, 5:5 and 7.5:7.5 and 10:10 weight per cent. The flammability properties of the developed composites were examined, using a cone calorimeter. The controlling parameters were analysed using the Taguchi robust design method. The ANOVA showed that time had the greatest influence on the total heat release rate (81.72%). The weight per cent reinforcement type (10.37%) and reinforcement type (5.28%) had smaller influences on the heat release rate. The S/N ratio obtained, using optimal testing shows that time had the greatest influence on the total heat release rate, followed by weight per cent of reinforcement type, while reinforcement type had the least influence. The corresponding multiple regression models for total heat released revealed that the total heat release rate increased with an increase in time and reinforcement type and decreased with an increase in weight per cent of the fire retardant additive material. Conclusion This work indicated that the parameter design of the Taguchi method provided an efficient methodology for the analyses of the effects of thermal degradation parameters of composites. The controlling parameters of time, the weight of reinforcement material and the type of reinforcement material had significant contributions to the value of heat production during composites thermal decomposition. Time had the greatest contribution, followed by the weight of reinforcement type, and type of reinforcement material.

Fabrication of Diaminodiphenylmethane Modified Ammonium Polyphosphate to Remarkably Reduce the Fire Hazard of Epoxy Resins

A novel diaminodiphenylmethane (DDM) modified ammonium polyphosphate (APP) flame retardant, DDP, was successfully synthesized via ion-exchange reaction. DDP was introduced into epoxy resins (EPs) to reduce flammability. A comparable level of DDP exerts better flame-retardant and smoke suppression efficiencies in EP than APP. An EP blend containing 15 wt% DDP displays a limiting oxygen index (LOI) value of 37.1% and a UL 94 V-0 rating, and further exhibits a 32.3% reduction in total heat release and a 48.0% reduction in total smoke production compared with pure EP. The presence of DDP greatly facilitates char formation during combustion, and the char mass from thermal decomposition of an EP blend is 37.8% smaller than that of an EP blend containing 15 wt% DDP at 800 °C. The incorporation of DDP into EP blends has a smaller impact on the glass transition temperature and tensile strength than those of a comparable level of APP. This reflects the better compatibility of DDP with the EP matrix compared with that for APP.

Bench-scale experimental study on the fire behavior of electric cable arrays by considering different layouts

The effect of different cable layouts on the fire behavior of electric cable arrays was experimentally studied. The influence of external heat flux on cable fire characteristics was investigated. Several parameters for electrical cables such as the post-burning morphology, ignition time, heat release rate, peak heat release rate and total heat release were obtained. The results show that cable layouts could affect cable charring degrees according to the post-burning morphology. A linear relationship was found in the transformed form of time to ignition and radiant heat flux, and the critical radiant heat flux value for the single cable array appeared smaller than that for the other two layouts. The peak heat release rate for Cables A–D with the single array presents the increasing trend with an increase in radiant heat flux, while the two parallel and intersectional cable arrays present the different trends. Moreover, the total heat release values of Cables A–D in the different cable layouts were analyzed. This work provides the basic data and preliminary investigation to fire engineering of cable arrays with the different layouts.

Self-assembled bio-based coatings for flame-retardant and antibacterial polyester–cotton fabrics

There are many defects in the post finishing flame-retardant modification of polyester–cotton (CT) fabric, leading to shortcomings such as single function and low flame-retardant efficiency, which still need to be solved urgently. Herein, a bio-based flame-retardant and antibacterial coating consisting of phytic acid and DL-arginine was deposited on CT fabrics using layer-by-layer assembly to obtain a flame-retardant and antibacterial CT fabric. Fourier transform infrared spectroscopy confirmed that the assembled coating was successful deposited on the CT fabric. The thermogravimetric analysis revealed that the number of bilayers had no significant effect on the degradation temperature of the coated CT fabric; however, it significantly improved the charring effect of the sample, wherein the char rate of the CT fabric coated with 20 bilayers increased from 0.11 to 8.67 wt% compared with uncoated CT fabric at 700°C. In addition, the limiting oxygen index of the CT fabric coated with 20 bilayers increased to 32.0 ± 0.3%. Furthermore, the vertical results revealed that the CT fabric coated with five bilayers attained the UL-94 V-1 grade. The heat release rate (HRR) and the total heat release (THR) of the coated CT fabric were significantly decreased compared to those of the uncoated CT fabric. In particular, the HRR and THR of the CT fabric coated with five bilayers reduced by 28.97% and 30.49%, respectively. Furthermore, the coated CT fabric exhibited an obvious antibacterial effect on Staphylococcus aureus, and the inhibitory ring increased from 0 to 4.0 mm with an increase in bilayers to 20. This study describes a facile method of flame-retardant and antibacterial modification of CT fabric using biological materials.

Enhancing the Fire Safety and Smoke Safety of Bio–Based Rigid Polyurethane Foam via Inserting a Reactive Flame Retardant Containing P@N and Blending Silica Aerogel Powder

Rigid polyurethane foams (RPUFs) are widely used in many fields, but they are easy to burn and produce a lot of smoke, which seriously endangers the safety of people’s lives and property. In this study, tetraethyl(1,5–bis(bis(2–hydroxypropyl)amino)pentane–1,5–diyl)bis(phosphonate) (TBPBP), as a phosphorus–nitrogen–containing reactive–type flame retardant, was successfully synthesized and employed to enhance the flame retardancy of RPUFs, and silica aerogel (SA) powder was utilized to reduce harmful fumes. Castor oil–based rigid polyurethane foam containing SA powder and TBPBP was named RPUF–T45@SA20. Compared with neat RPUF, the obtained RPUF–T45@SA20 greatly improved with the compressive strength properties and the LOI value increased by 93.64% and 44.27%, respectively, and reached the V–0 rank of UL–94 testing. The total heat release (THR) and total smoke production (TSP) of RPUF–T45@SA20 were, respectively, reduced by 44.66% and 51.89% compared to those of the neat RPUF. A possible flame–retardant mechanism of RPUF–T45@SA20 was also proposed. This study suggested that RPUF incorporated with TBPBP and SA powder is a prosperous potential composite for fire and smoke safety as a building insulation material.

Synthesis and characterization of flame-retardant-wrapped carbon nanotubes and its flame retardancy in epoxy nanocomposites

A novel phosphorus-silicon containing flame-retardant DOPO-V-PA was used to wrap carbon nanotubes (CNTs). The results of FTIR, XPS, TEM and TGA measurements exhibited that DOPO-V-PA has been successfully grafted onto the surfaces of CNTs, and the CNTs-DOPO-V-PA was obtained. The CNTs-DOPO-V-PA was subsequently incorporated into epoxy resin (EP) for improving the flame retardancy and dispersion. Compared with pure EP, the addition of 2 wt% CNTs-DOPO-V-PA into the EP matrix could achieve better flame retardancy of EP nanocomposites, such as a 30.5% reduction in peak heat release rate (PHRR) and 8.1% reduction in total heat release (THR). Furthermore, DMTA results clearly indicated that the dispersion for CNTs-DOPO-V-PA in EP matrix was better than pristine CNTs.

Improvement of Flame Retardancy of Polyurethane Foam Using DOPO-Immobilized Silica Aerogel

In this work, silica aerogel was modified by 9,10-dihydro-9-oxa-10-phosphaphenanthrene-1-oxide (DOPO). Then DOPO-immobilized silica aerogel nanoparticles were used as a flame retardant to prepare flame-retardant polyurethane foams. Microscale combustion calorimeter and cone calorimeter tests were employed to evaluate the flame retardancy of polyurethane foams. It was found that both the heat release rate and the total heat release of the composites were reduced with the incorporation of DOPO immobilized silica aerogel. It is speculated that the DOPO-immobilized silica aerogel nanoparticles can inhibit the degradation of polyurethane and catalyze the formation of carbonaceous carbon on the surface.

Analysis of Combustion and Smoke Characteristics According to the Aging of Class 1E Cables in Nuclear Power Plants

In this study, combustion and smoke characteristics according to the aging of class 1E cables in nuclear power plants were analyzed through a cone calorimeter test. In the case of combustion characteristics, during the early period, which was the first peak of the heat release rate, the peak value of the non-aged cable was higher by approximately 20-50 kW/m² than that of aged cables. However, in the mid-late periods, which was the second peak, the value of the aged cables were higher than the non-aged cable due to the decrease in flame retardant performance with aging deterioration. In addition, the duration of the char layer of the aged cables was shortened by 200 s than that of the non-aged cables due to the unstable formation of char layer. The total heat release measured was approximately 1.4 times higher in the aged cables than in the non-aged cables. In the case of smoke characteristics, the smoke production rate and total smoke release show a similar trend with the heat release rate and total heat release. The total smoke release of the aged cables was measured to be higher than that of the non-aged cables. The tendency of the smoke factor increased with aging deterioration, and the values of the smoke factor in the aged cables beyond 4 years were approximately 1.76-2.0 times different from those in the non-aged cables. Consequently, the smoke risk increased with aging deterioration. Therefore, the risk of heat and smoke release increased as aging progressed.